Thanks to everyone for the responses so far.

To give you all more information....

Our small door company produces doors for contractors. We don't do ANY
finishing for customers. The doors are final sanded and it's up to the
customer to stain/finish them. I DO however try stains from time to
time to inspect the sanding quality. Although the suggestions on
conditioners and sealers is very good advice.....I need a better final
sanding solution to be able to hand off to the customer so they can be
ready to stain once they receive the doors with no work having to be
done by themselves.

More info on our machines....

The main machine in question is a Unique GT250 and a Unique 336-4
Shape/Sand. Both setups....easily 100k all said with tooling. So as far
as the quality of cut....our tooling is carbide insert tooling that is
clearly sharp enough. We run the cutters at 7000/8000 rpm's....so speed
isn't an issue. And never have we ever been able to cut CROSS/END
grain, even when everything was brand new, we could never stain end
grain without problems. Even the machine manufacturer agrees that it's
not possible....that's the reason we bought the shape and sand machine
in the 1st place.

On our shape and sand the feed rate is 20 fpm and the cutters are run
ar 7000rpm. The cuts come out fine. With the grain cuts can be stained
to a somewhat acceptable level with little or no sanding. But again,
the problem is the end grain. For the sanders...the sanding head is
with 1000th of an inch match to our cutting profile. We run the sanders
at 1350 rpm between 2 stations. The first station hits with 150g and
the second with 180g.

Something that is interesting......some have mention going up very high
with the sanding on the end grains. I need some more specifics....;

Are you guys suggesting like going to 220/320g or even higher?
400/600g?

Thanks for the feedback.